Acessibilidade / Reportar erro

Colonization dynamics of Acidovorax citrulli in melon

Dinâmica de colonização de Acidovorax citrulli em meloeiro

Abstracts

The aim of this work was to investigate the ability of Acidovorax citrulli, the causal agent of bacterial fruit blotch (BFB) of cucurbits, to colonize melon tissues. Under greenhouse conditions leaves and seeds were inoculated with a spontaneous mutant of A. citrulli (group I) resistant to rifampicin (Ac1Rif), and samples of hypocotyls, cotyledonary leaves, roots, leaves and stems were processed at three-day intervals. When the 1st pair of melon leaves had been inoculated, A. citrulli was only detected until the 10th pair of leaves (1.3 x 10³ CFU g-1 of leaf) and the consecutive stem (3.3 x 10³ CFU g-1 of stem) on the 30th day. However, after seed inoculation A. citrulli colonized the hypocotyl, roots, cotyledonary leaves, leaves and stems and was only detected until the 4th pair of leaves (1.62 x 10² CFU g-1 of leaf) and the consecutive stem (9.1 x 10¹ CFU g-1 of stem) on the 24th day post-inoculation. In conclusion, A. citrulli colonized different parts of the melon plant over time, depending on its initial location, leaves or seed. This confirms what has been observed in the field, that expanded leaves and stems are the main inoculum sources for melon blossoms and fruit, therefore providing scientific bases for developing more effective strategies for BFB management.

Cucumis melo; ecology; plant pathogenic bacteria; bacterial fruit blotch


Este trabalho investigou a habilidade de Acidovorax citrulli, agente causal da mancha-aquosa em cucurbitáceas, colonizar plantas de meloeiro. Em condições de casa de vegetação, folhas e sementes foram inoculadas com um mutante espontâneo de A. citrulli (grupo I) resistente a rifampicina (Ac1Rif) e a intervalos de três dias, amostras de hipocótilo, folhas cotiledonares, raízes, folhas ou ramos foram processadas. Após a inoculação no 1º par de folhas, A. citrulli foi detectada até o 10º par de folhas (1,3 x 10³ UFC g-1 de folha) e no ramo consecutivo (3,3 x 10³ UFC g-1 de ramo) aos 30 dias. A partir da inoculação das sementes A. citrulli colonizou efetivamente o hipocótilo, raízes, folhas cotiledonares, folhas e ramos, sendo a bactéria detectada até o 4º par de folhas (1,62 x 10² UFC g-1 de folha) e no ramo consecutivo (9,1 x 10¹ UFC g-1 e ramo) aos 24 dias após a inoculação. Pode-se concluir que A. citrulli colonizou diferentes partes do meloeiro ao longo do tempo, dependendo da localização do inóculo inicial, folhas ou sementes. Isto confirma o que tem sido observado nas condições de campo, ou seja, que folhas expandidas e ramos são fontes de inóculo para flores e frutos de melão, dando, portanto, suporte científico para o desenvolvimento de estratégias mais efetivas de manejo da mancha-aquosa do meloeiro.

Cucumis melo; ecologia; fitobactéria; mancha-aquosa


SHORT COMMUNICATIONS COMUNICAÇÕES

Colonization dynamics of Acidovorax citrulli in melon

Dinâmica de colonização de Acidovorax citrulli em meloeiro

Aldenir de Oliveira AlvesI; André da S. XavierI; Ivanise O. VianaI; Rosa de L. R. MarianoI; Elineide Barbosa da SilveiraII

IDepartamento de Agronomia/Fitossanidade

IIDepartamento de Biologia/Microbiologia, Universidade Federal Rural de Pernambuco, 52171-900, Recife, PE, Brazil

ABSTRACT

The aim of this work was to investigate the ability of Acidovorax citrulli, the causal agent of bacterial fruit blotch (BFB) of cucurbits, to colonize melon tissues. Under greenhouse conditions leaves and seeds were inoculated with a spontaneous mutant of A. citrulli (group I) resistant to rifampicin (Ac1Rif), and samples of hypocotyls, cotyledonary leaves, roots, leaves and stems were processed at three-day intervals. When the 1st pair of melon leaves had been inoculated, A. citrulli was only detected until the 10th pair of leaves (1.3 x 103 CFU g-1 of leaf) and the consecutive stem (3.3 x 103 CFU g-1 of stem) on the 30th day. However, after seed inoculation A. citrulli colonized the hypocotyl, roots, cotyledonary leaves, leaves and stems and was only detected until the 4th pair of leaves (1.62 x 102 CFU g-1 of leaf) and the consecutive stem (9.1 x 101 CFU g-1 of stem) on the 24th day post-inoculation. In conclusion, A. citrulli colonized different parts of the melon plant over time, depending on its initial location, leaves or seed. This confirms what has been observed in the field, that expanded leaves and stems are the main inoculum sources for melon blossoms and fruit, therefore providing scientific bases for developing more effective strategies for BFB management.

Key words: Cucumis melo, ecology, plant pathogenic bacteria, bacterial fruit blotch.

RESUMO

Este trabalho investigou a habilidade de Acidovorax citrulli, agente causal da mancha-aquosa em cucurbitáceas, colonizar plantas de meloeiro. Em condições de casa de vegetação, folhas e sementes foram inoculadas com um mutante espontâneo de A. citrulli (grupo I) resistente a rifampicina (Ac1Rif) e a intervalos de três dias, amostras de hipocótilo, folhas cotiledonares, raízes, folhas ou ramos foram processadas. Após a inoculação no 1º par de folhas, A. citrulli foi detectada até o 10º par de folhas (1,3 x 103 UFC g-1 de folha) e no ramo consecutivo (3,3 x 103 UFC g-1 de ramo) aos 30 dias. A partir da inoculação das sementes A. citrulli colonizou efetivamente o hipocótilo, raízes, folhas cotiledonares, folhas e ramos, sendo a bactéria detectada até o 4º par de folhas (1,62 x 102 UFC g-1 de folha) e no ramo consecutivo (9,1 x 101 UFC g-1 e ramo) aos 24 dias após a inoculação. Pode-se concluir que A. citrulli colonizou diferentes partes do meloeiro ao longo do tempo, dependendo da localização do inóculo inicial, folhas ou sementes. Isto confirma o que tem sido observado nas condições de campo, ou seja, que folhas expandidas e ramos são fontes de inóculo para flores e frutos de melão, dando, portanto, suporte científico para o desenvolvimento de estratégias mais efetivas de manejo da mancha-aquosa do meloeiro.

Palavras-chave:Cucumis melo, ecologia, fitobactéria, mancha-aquosa.

Bacterial fruit blotch (BFB) caused by Acidovorax citrulli (Schaad et al.) Schaad et al. is one of the main problems facing melon crops in northeastern Brazil, especially in the rainy season. The main symptoms are found in the fruit as small, oily blotches, with or without halo, which rapidly progress and coalesce, becoming aqueous, light or dark brown blotches. Internally, the bacterium causes dry rot in the fruit pulp (Medeiros et al., 2009).

In the BFB cycle, contaminated seeds produce diseased plantlets. The bacterium spreads among the plantlets and infects a significant proportion of the seedlings. As the plants grow in the field, the pathogen spreads to new leaves and neighboring plants. Lesions on the leaves are the main source of inoculum for immature fruit. Ripe fruits exhibit the typical disease symptoms and seeds become infected (Mariano et al., 2001). Molecular, biochemical and host-range analysis of A. citrulli isolates showed the existence of two distinct groups: group I includes strains isolated mainly from non-watermelon plants, while group II includes strains isolated mostly from watermelon (Walcott et al., 2000, 2004; Bahar et al., 2010).

Under greenhouse conditions, colonization of A. citrulli group II has been quantitatively determined in leaves, seeds, blossoms and fruits of watermelon (Walcott et al., 2003; Lessl et al., 2007), while A. citrulli group I was qualitatively studied on leaves, seeds and fruits of melon (Silva Neto et al., 2006). In melon leaves, this scanning electron microscopy study showed that A. citrulli group I cells are preferentially located in protected sites of the phylloplane, such as depressions between epidermal cells, bases of the trichomes and around and within the stomata. Moreover, epiphytic and endophytic colonization was observed in melon seeds, in external and internal teguments, embryo and endosperm (Silva Neto et al., 2006). As far as we know, the other authors studying melon colonization by A. citrulli are Bahar and co-authors in Israel. According to them, A. citrulli group I has the ability to colonize and move through the xylem vessels of melon seedlings (Bahar et al., 2009).

Investigations into the ability of A. citrulli to colonize seeds, leaves and stems of melon plants and serve as inoculum source for fruit infection in the field are of great importance to a better understanding of the bacterial colonization dynamic, leading to more effective strategies for BFB management. Since we were not able to find any published studies on the quantification of A. citrulli colonization in melon plants, this was the aim of the present work.

Melon plants of a hybrid Yellow AF-646 (Sakata®) were grown in pots containing 3.5 kg of sterilized soil + substrate Basaplant (Base – Soluções em Substratos, Holambra. São Paulo, Brazil) (2:1) and kept in a greenhouse. Plants were conducted as single vines, tutored and the pots were placed in saucers which were maintained with water (subirrigation). All colonization studies were performed with an A. citrulli (group I) spontaneous mutant resistant to 100 ppm of rifampicin, named Ac1Rif, which showed growth in liquid medium and pathogenicity similar to the wild strain. Leaf inoculations were conducted between 07:00 and 10:00 h.

To study colonization of A. citrulli in leaves and stems the pathogen was cultivated on NYDA medium (Pusey & Wilson, 1984) for 36-48 h. The suspension was prepared in distilled water amended with Tween 20 (0.05%), and adjusted in a spectrophotometer (Analyser, model 500M, São Paulo, Brazil) to A570nm= 0.36, which corresponds to 3.4 x 107 CFU mL-1. The 1st pair of leaves of the 20 day-old melon plants was sprayed with the suspension and the plants were incubated in a moist chamber for 24 h prior to and post-inoculation (Silveira et al., 2003). Sampling of leaves and stems toward the plant apex was carried out at three-day intervals until the bacterium could not be detected in two successive samples. The 1st pair of leaves was analyzed on Day Zero (2 h following inoculation) and on Day 3. The experimental design was completely randomized, with four replications. The experimental unit was either the pair of leaves or its consecutive stem, to be analyzed at each sampling time. The experiment was carried out twice. At each evaluation, 0.5 g of fragmented samples were added to 4.5 mL of sterilized distilled water (SDW) in tubes, sonicated (Thorton T-7, Thorton Inpec Electronic LTDa, Vinhedo, São Paulo, Brazil) for five minutes at power 10, diluted until 10-3, and 10 µL of the suspensions plated on medium NYDA + Rif (NYDARif) with three replications. Incubation was carried out for 36 hours at 30ºC in B.O.D. (Biochemical Oxygen Demand) (Tecnal, TE-391, Campinas, São Paulo, Brazil), and the bacterial population of each sample was determined and expressed in CFU g-1.

To analyze the colonization of A. citrulli in the hypocotyls, roots, cotyledonary leaves, leaves and stems Yellow AF-646 (Sakata®) melon seeds were rinsed in running water for 10 minutes, dried at room temperature (25 ± 2ºC), immersed in the bacterial suspension (3.4 x 107 CFU mL-1) and submitted twice to vacuum infiltration (450 mg of Hg) for two minutes. Seeds were dried at room temperature for 16 h, planted as already described, and kept in greenhouse. Seeds were assessed on Day Zero (two hours after inoculation); hypocotyls were assessed on Day 6; roots were assessed on Day 9; cotyledonary leaves were assessed on Day 12; and leaves and consecutive stems were assessed from Day 15 until the bacterium could not be detected in two successive samples. At each evaluation, samples were processed as described above. The experimental design was completely randomized, with four replications. The experimental unit was the melon plant organ to be analyzed at each sampling time. The populations were transformed into log10 CFU g-1 of sample and analyzed using linear regression by the SAEG® 9.0 (Statistical and Genetic Analysis System, Universidade Federal de Viçosa, Minas Gerais, Brazil, 2005). Standard deviations of the means were also calculated.

In the 1st pair of leaves inoculated with the Ac1Rif suspension at 3.4 x 107 CFU mL-1, an initial population of 6.3 x 105 CFU g-1 of leaf was detected two hours after inoculation (Day Zero) (Figure 1). Three days after inoculation the size of the population on the 1st pair of leaves remained stable (3.98 x 105 CFU g-1 of leaf) and there was colonization of the consecutive stem, with 3.46 x 104 CFU g-1 of stem (Figure 1). Throughout the evaluations, a general decrease in population size was observed in the leaves, with a drastic reduction in the 3rd and 6th pairs of leaves and consecutive stems at the 9th and 18th days after inoculation (Figure 1). Ac1Rif colonization was detected within 30 days after inoculation in the 10th pair of leaves, with a population of 1.3 x 103 CFU g-1 of leaf. In this same time period, colonization in the consecutive segment of stem was 3.3 x 103 CFU g-1 of stem. Bacterial populations were not detected in the 11th and 12th pair of leaves after 33 days.


Seeds inoculated with Ac1Rif through vacuum infiltration (3.4 x 107 CFU mL-1) showed an initial population of 1 x 105 CFU g-1 of seed two hours after inoculation (Day Zero) (Figure 2). The bacterium colonized hypocotyl and roots, with populations of 2.81 x 104 CFU g-1 and 2.18 x 104 CFU g-1 of tissue, respectively. In cotyledonary leaves A. citrulli population reached 8.7 x 104 CFU g-1, from which point there was colonization of leaves and stems until reaching undetectable levels at the 5th pair of leaves and consecutive stem 27 days after inoculation. The last populations detected (24 days after inoculation) were 1.62 x 102 CFU g-1 of leaf in the 4th pair of leaves and 9.1 x 101 CFU g-1 of stem in the consecutive stem (Figure 2).


The colonization dynamics of Ac1Rif in leaves and stems of the melon plants shows that inoculation in the 1st pair of leaves maintained higher A. citrulli populations throughout the evaluations (Figures 1 and 2) than when the bacterium was seed inoculated. The initial populations in the 1st pairs of leaves of the two experiments were 6.3 x 105 and 2.57 x 104 CFU g-1 of leaf, decreasing to undetectable levels at 33 and 27 days after inoculation, respectively.

Symptoms of BFB were observed through the experiments. Leaf spots were observed up to the 5th and 1st pairs of leaves, following leaf or seed inoculation, respectively. Leaf lesions were initially light green and oily, turning dark, with or without halo. When seeds were inoculated, hypocotyls and cotyledonary leaves showed water-soaked lesions which progressed to a brown color. As expected, no symptoms were found in roots or stems.

The difference between the Ac1Rif initial population in the 1st pair of leaves 2 h after inoculation (Figure 1) in relation to the concentration of the applied suspension may have occurred through drift, cell death, cell adherence to leaf surface, localization on protected sites, penetration or even the low sensitivity of the quantification method for detection of viable but non-culturable cells, as observed in other plant pathogenic bacteria (Beattie & Lindow, 1999; Pujol et al., 2007).

The decrease in population size as the bacterium colonized the leaves and consecutive stems, until reaching undetectable levels at 11th pair of leaves and consecutive stem 33 days following inoculation (Figure 1), may be related to the phenological stage of the plant, and physiological differences among the leaves. Kinkel et al. (2000) found that old leaves of grass species (near the base of the plant) consistently had larger bacterial populations than young leaves at the apex of the plant. This may be attributed to differences in the exudation rate of nutrients correlated with the age of the plant (Weller & Saettler, 1980), micro-climatology associated with the position of the leaf (Burage, 1976) or an incomplete colonization of young leaves (Kinkel et al., 2000). Differences in the position of the leaf are strongly correlated with differences in the population of bacteria that colonize individual leaves over time (Kinkel et al., 2000).

The reduction in the Ac1Rif population on the 3rd and 6th pairs of leaves and consecutive stems (Figure 1) probably resulted from drastic alterations in temperature in the greenhouse, which reached approximately 41ºC, as the optimum temperature for the pathogen growth is 35ºC (Cavalcanti et al., 2005). When Ac1Rif was inoculated in the seeds, there was colonization of the hypocotyl and roots, an increase in the population in the cotyledonary leaves and subsequent colonization of leaves and stems (Figure 2). Leaf surface is considered a hostile environment for bacterial colonization due to the limited source of nutrients, exposure to rapid variations in temperature and relative humidity (Lindow & Brandl, 2003). Nevertheless A. citrulli exhibited higher adaptation to phyllosphere than to hypocotyls and roots. Silva et al. (2006) found that A. citrulli survived epiphytically for 54 days on leaves of melon plants under greenhouse and field conditions, with a population of 103 to 104 CFU g-1 of leaf, regardless of the concentration of the initial inoculum, and in the roots and rhizosphere in the same time period under greenhouse conditions, with populations of 102 to 103 CFU g-1 of root and 10 CFU g-1 of soil.

Higher populations of Ac1Rif in leaves and stems throughout the evaluations (Figures 1 and 2) were found when the bacterium was inoculated in leaves compared to seed inoculation. This may be explained by initial populations detected in the 1st pairs of leaves, in each inoculation method, which were 6.3 x 105 and 2.57 x 104 CFU g-1 of tissue, respectively. Since the plants were grown tutored and watered by subirrigation, there is a strong possibility that the colonization of leaves and stems was systemic or endophytic rather than epiphytic. This situation is different in melon fields, where inoculum arrives constantly on aerial plant parts that have indeterminate and horizontal growth, thus facilitating pathogen dissemination and colonization (Lessl et al., 2007).

The absence of BFB symptoms beginning at the 6th or 2nd pair of leaves after inoculation of leaves and seeds, respectively, may be attributed to the low bacterial concentration detected, 1.3 to 0.58 x 103 CFU g-1 of leaf, and to the low leaf-wetting conditions, explained by the subirrigation. Silveira et al. (2003) found symptoms of BFB on leaves of melon plants sprayed with A. citrulli (3.38 x 101 CFU mL-1) only when submitting them to a high leaf-wetting condition (moist chamber for 48 hours prior to and following inoculation). Also in the field, it is known that BFB epidemics develop when the rainy season favors a high humidity level inside canopy/in plantations.

Populations associated internally and externally with the leaves are likely to have continuity as a result of entry (ingression) or exiting (egression) processes in this organ. A number of studies suggest that the application of the pathogen on the plant surface results in internal colonization (Dane & Shaw, 1996; O'Brien & Lindow, 1989). Considering that application of Ac1Rif on the 1st pair of leaves was performed under high humidity conditions, there must have been considerable epiphytic multiplication and penetration of the bacterium through the stomata in the initial hours, as reported by Young (1974) and Silva Neto et al. (2006).

Our findings confirmed those reported by Bahar et al. (2009), which provided, for the first time, strong evidence that at least group I strains of A. citrulli possessed vascular infection ability in melon seedlings. They also showed that in the xylem vessel colonization Type IV pili may play an important role under sap flow conditions, while polar flagella could be more important for spread during periods when xylem flow is reduced (Bahar et al., 2010). Egression is also important in the ecology of plant pathogens. Yang et al. (2001) found that approximately 14% of the Xanthomonas citri subsp. malvacearum population was present on the leaf surface after its infiltration, indicating that egression has quantitative importance to the external population. This phenomenon may have also occurred when the seeds were inoculated with Ac1Rif. A. citrulli group I colonized different parts of the melon plant up to 33 days after inoculation, depending on its initial location, leaves or seed. This confirms what has been observed in field, that expanded leaves and stems are the main inoculum sources for melon blossoms and fruit, therefore providing scientific bases for developing more effective strategies for BFB management.

ACKNOWLEDGEMENTS

The authors acknowledge the Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq (PQ-304313/2005-0) for granting scholarships and the Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco – FACEP (APQ-0350-5.01/06) for financial assistance.

Received 11 June 2010

Accepted 13 December 2010

Author for correspondence: Elineide Barbosa da Silveira, e-mail: elineidebs@yahoo.com.br

Part of the Master Thesis of the first author. Universidade Federal Rural de Pernambuco. Recife PE. 2010.

TPP 133

Section Editor: Marisa A.S.V. Ferreira

  • Bahar O, Fuente LDL, Burdman S (2010) Assessing adhesion, biofilm formation and motility of Acidovorax citrulli using microfluidic flow chambers. FEMS Microbiology Letter 312:33-39.
  • Bahar O, Goffer T, Burdman S (2009) Type IV pili are required for virulence, twitching motility, and biofilm formation of Acidovorax avenae subsp. citrulli Molecular Plant-Microbe Interactions 22:909-920.
  • Beattie GA, Lindow SE (1999) Bacterial colonization of leaves: a spectrum of strategies. Phytopathology 89:353-359.
  • Burage SW (1976) Aerial microclimate around plant surfaces. In: Dickinson CH, Preece TF (Eds.) Microbiology Aerial Plant Surface. San Francisco. Academic Press. pp.173-184.
  • Cavalcanti MT, Silveira EB, Mariano RLR, Oliveira IV (2005) Crescimento de Acidovorax avenae subsp. citrulli sob diferentes temperaturas, pH, concentração de cloreto de sódio e fontes de carbono. Ciência Rural 35:1313-1318.
  • Dane F, Shaw JJ (1996) Survival and persistence of bioluminescent Xanthomonas campestris pv. campestris on host and non-host plants in the field environment. Journal of Applied of Bacteriology 80:73-80.
  • Kinkel LL, Wilson M, Lindow SE (2000) Plant species and plant incubation conditions influence variability in epiphytic bacterial population size. Microbial Ecology 39:1-11.
  • Lessl JT, Fessehaie A, Walcott RR (2007) Colonization of female watermelon blossoms by Acidovorax avenae subsp. citrulli and the relationship between blossom inoculum dosage and seed infestation. Journal of Phytopathology 155:114-121.
  • Lindow SE, Brandl MT (2003) Microbiology of the phyllosphere. Applied and Environmental Microbiology 69:1875-1883.
  • Mariano RLR, Silveira EB, Assis SMP, Gomes AMA, Oliveira IS, Nascimento ARP (2001) Diagnose e manejo de fitobacterioses de importância no nordeste brasileiro. In: Michereff SJ, Barros R (Eds.) Proteção de plantas na agricultura sustentável. Recife PE. Imprensa Universitária. pp. 141-169.
  • Medeiros FHV, Moraes ISF, Silva Neto EB, Silveira EB, Mariano RLR (2009) Management of melon bacterial blotch by plant beneficial bacteria. Phytoparasitica 37:453-460.
  • O'Brien RD, Lindow SE (1989) Effect of plant species and environmental conditions on epiphytic population sizes of Pseudomonas syringae and other bacteria. Phytopathology 79:619-627.
  • Pujol M, Badosa E, Montesinos E (2007) Epiphytic fitness of a biological control agent of fire blight in aple and pear orchards under Mediterranean weather conditions. FEMS Microbiology Ecology 59:186-193.
  • Pusey PL, Wilson CL (1984) Postharvest biological control of stone fruit brown rot by Bacillus subtilis. Plant Disease 68:753-756.
  • Silva VAV, Silveira EB, Mariano RLR (2006) Sobrevivência de Acidovorax avenae subsp. citrulli em meloeiro. Fitopatologia Brasileira 31:381-386.
  • Silva Neto EB, Silveira EB, Mariano RLR, Nogueira NL, Rossi ML, Santos LA (2006) Penetração e colonização de Acidovorax avenae subsp. citrulli em folhas, frutos e sementes de melão amarelo. Fitopatologia Brasileira 31:84-88.
  • Silveira EB, Michereff SJ, Mariano RLR (2003) Severidade da mancha-aquosa em meloeiro sob diferentes condições de molhamento foliar e concentração de inóculo de Acidovorax avenae subsp. citrulli. Fitopatologia Brasileira 28:171-175.
  • Walcott RR, Fessehaie A, Castro AC (2004) Differences in pathogenicity between two genetically distinct groups of Acidovorax avenae subsp. citrulli on cucurbit hozsta hosts?. Journal of Phytopathology 152:277-85.
  • Walcott RR, Gitaitis R, Castro AC (2003) Role of blossoms in watermelon seed infestation by Acidovorax avenae subsp. citrulli Phytopathology 93:528-534.
  • Walcott RR, Langston DB, Sanders FH JR, Gitaitis RD (2000) Investigating intraspecific variation of Acidovorax avenae subsp. citrulli using DNA fingerprinting and whole cell fatty acid analysis. Phytopathology 9:191-6.
  • Weller DM, Saettler AW (1980) Colonization and distribution of Xanthomonas phaseoli and Xanthomonas phaseoli var. fuscans in field-grown navy beans. Phytopathology 70:500-506.
  • Yang CH, Crowley DE, Borneman J, Keen NT (2001) Microbial phyllosphere populations are more complex than previously realized. Proceedings of the National Academy of Sciences USA 98:3889-3894.
  • Young JM (1974) Development of bacterial populations in vivo in relation to plant pathogenicity. New Zealand Journal of Agricultural Research 17:105-113.

Publication Dates

  • Publication in this collection
    10 Mar 2011
  • Date of issue
    Dec 2010

History

  • Received
    11 June 2010
  • Accepted
    13 Dec 2010
Sociedade Brasileira de Fitopatologia Sociedade Brasileira de Fitopatologia, SGAS 902 Edifício Athenas - Bl. B, Salas 102/103, 70390-020 Brasília - DF Brasil, Tel: (55 61) 3225-2421 - Brasília - DF - Brazil
E-mail: sbfito@sbfito.com.br